Ocean acidification - text, video, and laboratory resources

SUMMARY

This resource offers text, audiovisual, and laboratory-based materials to aid students in understanding the basic concepts and implications of the increasing ocean acidity (reduction in pH) that results from increases in atmospheric carbon dioxide.

GOALS

The text article on ocean acidification is designed to convey an understanding of ocean carbonate chemistry, its changes in response to rising atmospheric CO2, and the consequent effects on marine organisms. The audiovisual material complements this description by providing a graphic illustration of the process. Laboratory exercises are designed to familiarize students with the chemistry involved in acidification and its effects on calcium carbonate shells.

ACTIVITY DESCRIPTION AND TEACHING MATERIALS

Ocean Acidification is a potentially serious consequence of continuing CO2 emissions that may rival global warming in terms of its eventual impact, but has received much less emphasis. This teaching resource, which is designed to focus attention on the problem, can be implemented in a short version requiring 1-2 hours or less, or a more extended version operating over 2 days.The short version involves a CAMEL article, a video, and a discussion period.The extended version entails the addition of a series of laboratory exercises.

The article, Ocean Acidification - "the other CO2 problem", describes the scientific evidence underlying ocean acidification and its consequences, including carbonate chemistry and effects on marine life.The video illustrates major points described in the article.CAMEL already lists several excellent videos on this topic, but their effect is limited by their brevity. The video described here, Acid Test -the global challenge of ocean acidification, is a 21 minute long, graphic depiction of what happens to sea creatures in an acidifying environment.Narrated by Sigourney Weaver, it interweaves powerful images with commentary by experts on ocean acidification and a commercial fisherman whose livelihood depends on the sea.The article and video can be followed by a discussion at a level appropriate for the particular audience, including the quality of the evidence, and the implications of different future levels of CO2.

One aspect of the video is problematic for a teaching exercise.From 17:20 to about 19:40, it deviates from a description of the evidence to instead advocate specific energy policies supported by the Natural Resources Defense Council (NRDC), the producer of the video.If this section is to be seen and heard, it would be a good idea, when the film is being discussed, to alert audiences beforehand about this portion, indicating that this is the particular position of the film producer, and that presenting the film should not be interpreted as an endorsement of that position.Otherwise, the exercise will be seen as too political.An alternative is to mute the audio for the advocacy portion; this can be done starting after Sigourney Weaver has stated, "the only way to stop acidification is to emit less carbon dioxide", with audio resumed when the screen shows the statement, "It Can Be Done".

The website for the video also lists other teaching resources.In particular, the link Download an ocean acidification kit can be visited for a set of laboratory exercises focused on ocean chemistry and the effects of reduction in pH on the shells of marine organisms.Details of the experiments, anticipated outcomes, and explanations can be found at this site.

Students exposed to the short version (article plus video) should come away with a vivid impression of how the oceans will change in a world of increasing CO2.Those who participate in the laboratory exercises will emerge with a clearer understanding of how these changes are based on fundamental principles of chemistry.

TEACHING NOTES / CONTEXT FOR USE

The text, audiovisual presentation, and a subsequent discussion can be utilized as a short version of the resource, encompassed within one or two hours of teaching time. The two laboratory exercises require sessions on two separate days, plus time for preparation of the materials. Details on the laboratory component can be found in the linked website, including the required materials, preparation procedures, safety, and the specific laboratory operations to be performed.

ASSESSMENT

Assessments based on the text and audiovisual material will be based on teacher impressions from the ensuing discussion. The laboratory exercises involve specific questions and answers designed to judge student comprehension of the performed tasks.

REFERENCES AND RESOURCES

SHORT DESCRIPTION

Ocean acidification due to rising atmospheric CO2 and its consequences for marine organisms are described through a combination of text, audiovisual, and laboratory resources.